Controlling operation of a power converter based on grid conditions

1. A method of gating a switching element used in a power converter of a wind-driven power generation system, wherein the switching element has a current conduction capability, the method comprising: applying a first gating voltage to a switching element to turn the switching element on, the switching element being associated with a power converter of a wind-driven power generation system and said switching element being used to convert a first AC power signal provided from a rotor bus into a DC power suitable for a DC link or used to convert the DC power on the DC link to a second AC power signal provided to a line side bus, the first gating voltage being greater than a threshold voltage for the switching element; detecting a grid event associated with an electrical grid coupled to the wind-driven power generation system, wherein said grid event causes an increase in a current provided to the power converter; comparing the current provided to the power converter to a predetermined threshold; determining whether the current provided to the power converter exceeds the threshold; and in response to determining that the current provided to the power converter exceeds the threshold, applying a second gating voltage to the gate of the switching element during the detected grid event such that the current conduction capability of the switching element is increased, the second gating voltage being greater than the first gating voltage.

2. The method of claim 1 , wherein the magnitude of the second gating voltage is determined based at least in part on a rotor current.

3. The method of claim 1 , further comprising, subsequent to the grid event, applying the first gating voltage to the gate of the switching element.

4. The method of claim 1 , wherein the grid event is a low voltage ride through grid event or a zero voltage ride through grid event.

5. The method of claim 1 , wherein the switching element is an insulated-gate bipolar transistor.

6. The method of claim 1 , wherein the switching element is a silicon carbide metal-oxide-semiconductor field-effect transistor.

7. The method of claim 1 , wherein the first gating voltage and the second gating voltage are determined based at least in part on the switching element.

8. The method of claim 1 , wherein the first and second gating voltages are applied to the switching element in accordance with a pulse width modulation control scheme to convert a first type of power to a second type of power.

9. The method of claim 8 , further comprising applying an off voltage to the switching element, the off voltage being less than the threshold voltage.

10. A gate drive circuit for applying a gate voltage to a gate of a switching element, wherein the switching element has a current conduction capability, the gate drive circuit comprising: an active gate control circuit, the active gate control circuit configured to: apply a first gating voltage to a switching element to turn the switching element on, said switching element being used to convert a first AC power signal provided from a rotor bus into a DC power suitable for a DC link or used to convert the DC power on the DC link to a second AC power signal provided to a line side bus, the first gating voltage being greater than a threshold voltage for the switching element; detect a grid event associated with an electrical grid coupled to the wind-driven power generation system, wherein said grid event causes an increase in a current provided to the gate drive circuit; and apply a second gating voltage to the gate of the switching element during the detected grid event such that the current conduction capability of the switching element is increased, the second gating voltage being greater than the first gating voltage.

11. The gate drive circuit of claim 10 , further comprising a gate resistor coupled to the active gate control circuit; and wherein the first and second gating voltages are applied to the gate of the switching element via the gate resistor.

12. The gate drive circuit of claim 10 , wherein the active gate control circuit is further configured to monitor the current being supplied to the gate drive circuit, and compare the monitored current to a current threshold.

13. The gate drive circuit of claim 12 , wherein the active gate control circuit is configured to apply the second gating voltage to the gate of the switching element based at least in part on the comparison of the monitored current to the current threshold.

14. A bridge circuit used in a power converter of a power system, the bridge circuit comprising: a first transistor having a gate, wherein the first transistor has a first current conduction capability and said first transistor being used to convert a first AC power signal provided from a rotor bus into a DC power suitable for a DC link or used to convert the DC power on the DC link to a second AC power signal provided to a line side bus; a second transistor coupled in series with the first transistor, wherein the second transistor has a second current conduction capability and said second transistor being used to convert the first AC power signal provided from a rotor bus into the DC power suitable for the DC link or used to convert the DC power on the DC link to the second AC power signal provided to a line side bus; a diode coupled in parallel with the first transistor; a gate drive circuit configured to apply a voltage to the gate of the first transistor, the gate drive circuit comprising a gate resistor and an active gate control circuit; wherein the active gate control circuit is configured to: apply a first gating voltage via the gate resistor to the gate of the transistor to turn on the first transistor, the first gating voltage being greater than a threshold voltage for the first transistor; detect a ride through grid event associated with an electrical grid coupled to the power system, wherein said grid event causes an increase in a current provided to the power converter; responsive to detecting the grid event, apply a second gating voltage to the gate of at least one of the first transistor and the second transistor during the detected grid event such that at least one of the first current conduction capability and second current conduction capability is increased, the second gating voltage being greater than the first gating voltage.

15. The bridge circuit of claim 14 , wherein the active gate control circuit is further configured to monitor a current being supplied to the power converter, the active gate control circuit being further configured to compare the monitored current to a current threshold.

16. The bridge circuit of claim 15 , wherein the active gate control circuit is configured to apply the second gating voltage to the gate of at least one of the first transistor and the second transistor based at least in part on the comparison of the monitored current to the current threshold.

17. The bridge circuit of claim 14 , wherein the first transistor is an insulated-gate bipolar transistor, including a collector and a gate or a silicon carbide metal-oxide-semiconductor field-effect transistor.

18. The bridge circuit of claim 17 , where in the first transistor is an insulated-gate bipolar transistor, the bridge circuit further comprising a passive feedback element coupled between the collector and the gate of the first transistor.